Submission #1180545

#	Time	Username	Problem	Language	Result	Execution time	Memory
1180545		t_danh	Mecho (IOI09_mecho)	C++20	45 / 100	820 ms	131072 KiB

mecho

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*/
 
#include <bits/stdc++.h>
#define input  ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define endl '\n'
#define fi first
#define se second
#define eb emplace_back
#define pb push_back
#define ce cout << endl
#define FOR(i, l, r) for (int i = l; i <= r; i++)
#define FOR2(i, l, r) for (int i = l; i >= r; i--)
using namespace std;
using ll = long long;
using str = string;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
 
const ll N = 1e5+1;
const ll LOGN = 19;
const int INF = numeric_limits<int>::max();
const ll MOD = 998244353;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
char op[] = {'D','U','R','L'};
void solve() {
    int n , s;
    cin >> n >> s;
    vector<vector<char>> matrix(n,vector<char>(n));
    vector<pii> hives;
    pii mecho;
    pii end;
    FOR(i,0,n-1){
        FOR(j,0,n-1) 
        {
            cin >> matrix[i][j];
            if(matrix[i][j] == 'H') hives.pb({i,j});
            else if(matrix[i][j] == 'M') mecho ={i,j};
            else if(matrix[i][j] == 'D') end = {i,j};
        }
    }
    function<bool(int,int)> inside =[&] (int i ,int j){
        return (i > - 1 && i < n && j > -1 && j < n && matrix[i][j] != 'T' && matrix[i][j] != 'H' && matrix[i][j] != 'D' );
    };
    function<bool(int,int)> check =[&] (int time,int dist){
        return time / s < dist;
    };
    

    deque<pii> q;
    vector<vector<int>> bee_time(n,vector<int>(n,-1));


    for(auto &i : hives){
        q.pb(i);
        bee_time[i.fi][i.se] = 0;
    }
    while(!q.empty()){
        pii c = q.front();
        q.pop_front();
        for(int i = 0 ; i < 4 ;  i++){
            int x = c.fi + dx[i] , y = c.se + dy[i];
            if(inside(x,y) && bee_time[x][y] == -1){
                bee_time[x][y] = bee_time[c.fi][c.se] + 1;
                q.pb({x,y});
            }
        }
    }
    int l = -1 ;
    int h = n * n;
    while( l < h){
        int m = l + h + 1 >> 1;
        vector<vector<int>> mecho_time(n,vector<int>(n,INF));

        
        q.pb(mecho);
        mecho_time[mecho.fi][mecho.se] = 0;
        if(bee_time[mecho.fi][mecho.se] <= m) q.pop_front();
        while(!q.empty()){
            pii c = q.front();
            q.pop_front();
            for(int i = 0 ; i < 4 ; i ++){
                int x = c.fi + dx[i] , y = c.se + dy[i];
                if(inside(x,y) && mecho_time[c.fi][c.se] < mecho_time[x][y] &&check(mecho_time[c.fi][c.se] + 1,bee_time[x][y] - m)){
                    mecho_time[x][y] = mecho_time[c.fi][c.se] + 1;
                    q.pb({x,y});
                }
            }
        }
        bool reached = false;
        for(int i = 0 ; i < 4 ; i ++){
            int x = end.fi + dx[i],y = end.se + dy[i];
            if(inside(x,y) && check(mecho_time[x][y] , bee_time[x][y] - m)){
                reached = true;
            }
        }
        if(reached) l = m;
        else h = m - 1;
    }
    cout << l <<endl;
}




 
int main() {
    input
    const bool cap = true;


    if (cap)
        solve();    
    else {
        ll t;
        cin >> t;
        while (t--) solve();
    }
}

• Subtask 1: 45 / 100